It wasn't so crazy to imagine Keith Thurman getting in on the Floyd Mayweather Jr. sweepstakes or landing a million-dollar fight against a million-dollar fighter. Not as he was putting the finishing touches on the most artistic of his 22 victories, as Jesus Soto Karass fell back into the waiting arms of referee Jon Schorle after one last right to the temple and a left uppercut to his mug in December.

But the Clearwater native's consolation prize is headliner status tonight when he takes on dangerous veteran Julio Diaz at the StubHub Center in Carson, Calif., in a bout that will be broadcast on Showtime.

Thurman (22-0, 20 knockouts) returns to his quest to land his first major title fight, defending an interim WBA welterweight title he has held for almost a year.

"There's definitely a political game going on right now,'' Thurman said. "There's a lot of fighters to choose from in the welterweight division. It looks like they've put me on hold."

Though getting a fight with Mayweather was a long shot, Thurman's other targets fell through.

Shawn Porter, the IBF champ, declined a fight, preferring to let a meeting between the division's top two young stars percolate into big bucks. Porter instead scored a technical knockout victory against Paulie Malignaggi.

WBA champion Marcos Maidana, whom Thurman almost fought last year, won the Mayweather sweepstakes. Mayweather will fight Maidana on May 3 to unify the WBC and WBA welterweight titles.

Sweepstakes runnerup Amir Khan decided on 33-year-old Luis Collazo. The guy Maidana beat for the WBA title, Adrien Broner, signed up to fight Carlos Molina, who lost his last fight to Khan.

Patience waning, Thurman hangs around the edges.

"I'm definitely in the mix, even if I'm in the background,'' he said. "Keith Thurman has arrived to the party, even if nobody wants to talk to me."

Once the crowded welterweight ring was cleared, Thurman was left with Diaz, a solid 34-year-old and former lightweight title holder who has competitive decisions to Porter and Khan his last two times out but remains dangerous. In 2012, when Diaz fought Porter for the first time, he scored a draw. Many thought Diaz won.

"It's a great fight; I'm looking forward to it, and I plan on outclassing the veteran,'' said Thurman, who continues to unveil facets to his game.

"I'm 25 years old. I wouldn't say I'm coming into my prime, but we're edging towards it. You can see it."